• Journal of Power Electronics
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• 제14권5호
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• pp.827-833
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• 2014

This study proposes a coupled inductor method for the parallel operation of a power conditioning system (PCS). When primary and secondary currents flow in the same direction in a coupled inductor, total flux and inductance are cancelled; when currents flow in opposite directions, each flux becomes an individual inductor. These characteristics are applied in the parallel operation of a PCS. To connect at a grid code, abnormal current, which is barred under the grid connection code, is blocked by using a coupled inductor. A design based on the capacity and current duration time of a PCS is verified through hardware implementation. Experiment results show the effectiveness of variance reduction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.385-387
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• 1994

Optical interconnections are more attractive than electronic interconnections because of their higher speed, freedom from planar constraints, immunity to electromagnetic interference effects and higher interconnection capacity. Volume hologram is one of the best way to implement optical interconnections. Diffraction efficiency and crosstalk effect are very important things for ensuring independent interconnections. Recently, a general systematic method that can handle a large number of superposed volume gratings in anisotropic host material is presented. In this study for numerical analysis of diffraction, above method is programmed in general form near Bragg angle. Diffraction orders for variation of grating strength are determined by comparing with the coupled-mode method. The effects of parameter variation are considered. Parameters include vertical and azimuthal incident angle, wavelength and interaction length. Diffraction analyses are also performed for intra-mode and inter-mode diffractions.

• 대한기계학회논문집A
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• 제31권10호
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• pp.981-985
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• 2007

We present a MEMS-based portable Direct Methanol Fuel Cell (micro-DFMC), featured by a platinum sputtered microcolumn electrode and a built-in fuel chamber containing a limited amount of methanol fuel. Also presented is a micro-DMFC stack structure having a common electrolyte sandwiched by the microcolumn electrodes. The single cells with ME16 and PE16 electrodes show the maximum power densities of $31.04{\pm}0.29{\mu}W/cm^2$ and $9.75{\pm}0.29{\mu}W/cm^2$, respectively; thus indicating the microcolumn electrode (ME16) generates the power density (3.2 times) higher than the planar electrode (PE16). The single cell tests of ME16 and ME4 electrodes (Fig.8) show the maximum power of $31.04{\pm}0.29{\mu}W/cm^2$, and $25.23{\pm}2.7{\mu}W/cm^2$, respectively; thus demonstrating the increased window frame reduces the normalized standard power deviation (standard deviation over the average power). The normalized deviation of 0.11 in ME4 cell has been reduced to 0.01 in ME16 cell due to the increased window frames. The maximum power density of 4-cell stack is 15.7 times higher than that of the single cell. 4-cell stack produces the power capacity of 20.3mWh/g during 980min operation at the voltage of 450mV with the load resistance of $800{\Omega}$.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4529-4536
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• 2010

본 논문에서는 배전계통 모의장치와 태양광전원 모의장치, LabVIEW를 이용한 감시제어장치로 구성된 태양광전원 계통연계 시험장치를 제작하여, 태양광전원의 연계용량과 계통의 선로 구성특성, 역율(역율1, 지상/진상역율)의 3가지 Parameter에 대한 태양광전원의 정상상태 운용특성을 모의하였다. 즉, 태양광전원의 연계 운용이 배전계통(수용가)에 미치는 영향과 배전계통이 태양광전원에 미치는 영향을 분석하여, 태양광전원의 계통연계 운용 시에 발생 가능한 기술적인 사항을 검토하였다. 그리고 계통연계 시험장치의 실험 결과치를 분석하기 위하여, 태양광전원 대응형 전압강하 계산 알고리즘을 제안하여, 이론적인 값과 시험치를 비교하여 태양광전원의 정상상태 특성에 대한 시험결과의 유용성을 확인하였다.

• 한국농공학회논문집
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• 제65권2호
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• pp.59-71
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• 2023

As the frequency of drought increases due to climate change, water scarcity in agriculture would be a main issue. However, it seems difficult to solve the water scarcity by securing alternative water sources. The aim of this study is to analyze optimal water supply capacity of agricultural reservoir for emergency operation connecting reservoirs and dams. First, we simulated the water storage of agricultural reservoir playing the role emergency water supplier to other water facility such as dams and other reservoirs. In particular, the results of simulation of water storage through K-HAS model was calibrated using the optimization process based on ratio correction factors of outflow and inflow. Finally, the optimal amount of water supply securing water supply reliability in emergency interconnection operation was analyzed. The results of this study showed that Janchi reservoir could supply 12.8 thousand m³/day maintaining 90 % water supply reliability. The result of this study could suggest the standard for connecting water facilities as emergency water supply.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.109-120
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• 2017

The behavior of moment resistant steel structures depends on both the beam-column connections and columns foundations connections. Obviously, if the connections can meet the adequate ductility and resistance against lateral loads, the seismic capacity of these structures will be linked practically to the performance of these connections. The shape memory alloys (SMAs) have been most recently used as a means of energy dissipation in buildings. The main approach adopted by researchers in the use of such alloys is firstly bracing, and secondly connecting the beams to columns. Additionally, the behavior of these alloys is modeled in software applications rarely involving equivalent torsional springs and column-foundation connections. This paper attempts to introduce the shape memory alloys and their applications in steel structural connections, proposing a new steel column-foundation connection, not merely a theoretical model but practically a realistic and applicable model in structures. Moreover, it entails the same functionality as macro modeling software based on real behavior, which can use different materials to establish a connection between the columns and foundations. In this paper, the suggested steel column-foundation connection was introduced. Moreover, exploring the seismic dynamic behavior under cyclic loading protocols and the famous earthquake records with different materials such as steel and interconnection equipment by superelastic shape memory alloys have been investigated. Then, the results were compared to demonstrate that such connections are ideal against the seismic behavior and energy dissipation.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1814-1821
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• 2012

본 논문은 국내에서 설비용량 20MW 이상의 신재생발전기에 대해 계통연계 유지조건을 의무화하는 송배전용 전기설비 이용규정이 2012년부터 적용됨에 따라 이를 모의해석 기반의 풍력발전기 계통연계 검토 시에 고려하기 위한 풍력발전기의 LVRT(Low Voltage Ride Through) 전사모형을 개발하고 이를 풍력발전기가 연계된 전력계통의 성능평가에 적용하여 전사모델의 유용성을 검증한 후 전력계통의 대표적인 상정고장에 적용하여 국내 풍력발전기 계통연계 유지조건의 적용효과를 분석하였다.

• 한국위성정보통신학회논문지
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• 제10권1호
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• pp.12-16
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• 2015

본 논문에서는 아마추어 무선 HR(HAM Radio)을 기반으로 구축되는 새로운 무선 재난통신망인 이동단말용 위성 통신 무선패키지 시스템을 소개하고, D2D 다중 홉 기반의 재난통신망 접속에서 D2D 단말이 인접 기지국과 D2D 그룹들에 의해 간섭을 받는 간섭 시나리오를 구성하였다. 이러한 간섭 시나리오에서 D2D 단말이 재난통신시 필요한 채널용량 확보하고 재난통신망에 원활하게 접속, 통신할 수 있도록 주파수 재할당 방법을 제시하였고, 제안한 기법의 성능을 컴퓨터 시뮬레이션을 통해 기존 알고리즘 대비 시스템 Throughput 성능 개선 및 BER 성능에서 최대 1.5dB 이득이 있음을 확인하였다.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.31-39
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• 2005

This paper illustrates a tie line constrained equivalent assisting generator (TEAG) model considering forced outage rates of transmission systems for reliability evaluation of interconnected power systems. Interconnections between power systems can provide improved levels of reliability. It is expected that the TEAG model developed in this paper will prove useful in the solution to problems related to the effect of transmission system uncertainties in the reliability evaluation of interconnected power systems. It is important that interconnection between power systems can provide the improved levels of reliability. Therefore, It is expected that the TEAG model developed in this study will provide some solution among many problems for interconnected power systems as an optimal tie line capacity and a connected point between assisting systems and assisted system. The characteristics and validity of this developed TEAG considering transmission systems are introduced by case study of three IEEE MRTS interconnected.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.1-12
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• 2021

MVDC 배전기술은 현재 급격하게 도입되고 있는 태양광전원의 접속지연 문제를 해결하기 위한 효과적인 대안으로 평가되고 있지만, DC 배전망용 기기들을 개발해야 하므로 DC 배전망의 구축비용은 경제적인 측면에서의 문제점을 가지고 있다. 따라서, 본 논문에서는 태양광전원의 수용을 위한 MVDC 배전망의 도입 타당성을 평가하기 위하여, 태양광전원 단지를 용량에 따라 규모별로 정의하고, 이를 수용하기 위한 배전망을 건설하는 경우에 대하여 규모별로 수용성 모델을 제시한다. 이 모델은 배전망의 전원공급방식에 따라 AC 및 DC 배전망으로 구분되며, 수용할 태양광전원 단지의 용량에 따라 수백 MW급은 대규모, 수십 MW급은 중규모, 수 MW급은 소규모로 정의된다. 또한, 본 논문에서는 AC 및 DC 배전망의 건설비, 전력변환설비의 교체비, 운용비로 구성된 비용요소와 태양광전원의 발전수익에 따른 전력량 요금 및 REC 요금으로 구성된 편익요소를 고려하여 MVDC 배전망의 경제성평가 모델링을 제시한다. 이를 바탕으로 현재가치 환산법과 원금균등상환 방식을 이용하여 MVDC 배전망의 경제성을 평가한 결과, 태양광전원의 수용 규모에 따라 일정 연계거리 이후에서는 DC 배전망의 구축비용이 기존의 AC 배전망보다 경제적임을 알 수 있어, 본 논문에서 제시한 경제성평가 모델링의 유용성을 확인하였다.